A PBR map with Principled shader doesn't add value to the object
The normal map is ok, it only changes the light reflections according to the faked angle of incidence, but it actually doesn't move any vertex of the mesh. Maybe what you are looking for is a displacement effect: you can subdivide your mesh (the more subdivided, better the result but heavier the mesh) and add a displace modifier, using your specular map as input and trimming the strenght value to a quite low level: in this way you will have a real vertices roughness, that may help the realistic effect.